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Exposure Compensation

February 1, 2010 Leave a comment Go to comments

You may have already seen the +/-  on your camera and wondered what it means exactly. You may have even accidentally set it and now your pictures aren’t turning out great. So what does it mean?

Let’s first start with how your camera meters.

The light meter in your camera is pretty advanced. I am going to go ahead and assume you are shooting in Av Mode (why wouldn’t you be?). You have your ISO set and your Aperture dialed in to f8 (just a random example). What happens next is that the camera measures the light and taking into account the aperture and ISO you have set, adjusts the corresponding shutter speed so you get the proper exposure. All before you press the shutter.

That isn’t even the advanced part though. Your camera likely has a few different styles of metering. Chances are you only use one and it’s probably the most advanced. It’s called Matrix Metering (or something similarly awesome/confusing depending on your camera manufacturer).

Without going into too much detail Matrix Metering takes into account the entire scene, calculates all the lights and darks and determines the best exposure. And it’s very good at it’s job. However, it isn’t always perfect and it doesn’t really know your intention so we get something called Exposure Compensation (again, it may be called something else according to manufacturer). Exposure Compensation is essentially a manual override of the camera’s metering. Sort of.

The camera still meters normally but you tell it to compensate with more or less light. Let’s say you are shooting outside in the snow for example. Your camera is going to see a lot of bright light and therefore try and limit the amount coming in. The end result might very well be that your kid’s smiling face is too dark and not visible. That’s no good.

So in this case you would dial the camera’s Exposure Compensation over to +1 and see what happens. Let me ruin the surprise- it will determine the amount of light it would like and then allow twice as much to come in (+1 means one f-stop worth which means double- don’t worry about that right now). If you tell it to go to +2 it will let in 4x the light. You can go the other direction as well and dial in -1 or -2.

The good news is that your camera will break down the increments into either 1/3 or 1/2 for a much more subtle result. That comes in handy.

Have a look at the mundane picture above to see this in action (click on the picture for the large size). The centre shot represents the exposure as the camera determined and the +/- on either side represents the extra stops. With the fairly bright white wall dominating the frame the camera’s best guess is a little too dark for my liking. (The +1 is too much though- I would probably go with +1/3).

I use exposure compensation all the time. Have a look for it on your camera. If you can’t find it head to the bathroom and consult your manual (Click Here).

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